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There is a high prevalence of treatment-resistant hypertension among patients with chronic kidney disease. This study identifies associations of various factors with treatment-resistant hypertension in this group.

Patients with chronic kidney disease are at risk for treatment-resistant hypertension, although certain subgroups carry a higher risk than others, researchers found.

The rate of apparent treatment-resistant hypertension was 28.1% among those with chronic kidney disease and 13.6% among those with normal kidney function, according to Paul Muntner, PhD, of the University of Alabama at Birmingham, and colleagues.

Within the group with chronic kidney disease, however, a lower risk of treatment-resistant hypertension was seen in women (prevalence ratio 0.87) and greater risks were seen in relation to black race, larger waist circumference, diabetes, a history of myocardial infarction or stroke, statin use, and worsening renal function (prevalence ratios 1.13 to 2.24), they reported online in the Clinical Journal of the American Society of Nephrology.

The findings "indicate that apparent treatment-resistant hypertension is a common condition among individuals with chronic kidney disease, suggesting the need for greater awareness of this comorbidity among clinicians," Muntner and colleagues wrote.

"Furthermore," they wrote, "the results of this study emphasize the need for the development and dissemination of appropriate therapeutic regimens for chronic kidney disease patients with apparent treatment-resistant hypertension."

A previous analysis of data from the National Health and Nutrition Examination Survey (NHANES) showed that the odds of having treatment-resistant hypertension were greater among individuals with an estimated glomerular filtration rate (eGFR) under 60 mL/min/1.73 m2 or an albumin-to-creatinine ratio (ACR) above 300 mg/g, but the categories of renal function were not broken down any further.

To look at the relationships between different levels of renal function and treatment-resistant hypertension, Muntner and colleagues examined data from 10,700 participants in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study who were being treated for hypertension with one or two classes of drugs. The study includes black and white individuals 45 and older.

Nearly one in every three patients (29%) had chronic kidney disease, defined as an eGFR below 60 mL/min/1.73 m2 or an ACR of at least 30 mg/g.

The overall rate of apparent treatment-resistant hypertension -- defined as a systolic blood pressure of at least 140 mm Hg and/or a diastolic pressure of at least 90 mm Hg despite use of three or more antihypertensive drug classes, or any blood pressure with use of at least four antihypertensive classes -- was 17.9%.

The rate increased across categories of declining kidney function, however:

For eGFRs of at least 60 mL/min/1.73 m2, the rate of treatment-resistant hypertension was 15.8%

For eGFRs of 45 to 59, the rate was 24.9%

For eGFRs of less than 45, the rate was 33.4%

And for ACRs of less than 10, 10 to 29, 30 to 299, and 300 mg/g or greater, the rates were 12.1%, 20.8%, 27.7%, and 48.3%, respectively.

More than half (56.4%) of patients who had the worst kidney function according to both measures also had treatment-resistant hypertension.

The authors acknowledged that the study was limited by the cross-sectional design, which made the direction of the associations unclear. In addition, blood pressure, eGFR, and albuminuria were assessed at a single time point, and there was a lack of information on medication dosing and on possible secondary causes of treatment-resistant hypertension.

This research project is supported by a cooperative agreement from the National Institute of Neurological Disorders and Stroke. Additional funding was provided by an investigator-initiated grant-in-aid from Amgen Corporation.

Muntner and one of his co-authors reported receiving grant support from Amgen. The other study authors reported relationships with AstraZeneca, Merck, the National Heart, Lung, and Blood Institute, Novartis, Takeda, Medtronic/Ardian, Daiichi Sankyo, Vivus, Medronic, Backbeat, Bayer, Pfizer, and Amgen.

Todd Neale, MedPage Today Staff Writer, got his start in journalism at Audubon Magazine and made a stop in directory publishing before landing at MedPage Today. He received a B.S. in biology from the University of Massachusetts Amherst and an M.A. in journalism from the Science, Health, and Environmental Reporting program at New York University.

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